Rollable Ultraviolet Photodetector Based on ZnAl‐Layered Double Hydroxide/Polyvinylidene Fluoride Membrane

Abstract

bandgap semiconductors, such as SiC, diamond, Ga 2 O 3 , GaN, ZnS, ZnO, or ZnSe, suffer from problems, such as low sensitivity, long response time, nonlinear photocurrent with incident optical power, and a complicated fabrication process. [3][4][5][6] In addition, the fabrication of a flexible or rollable UV photodetector with sufficient durability has not been reported, despite the great significance of sustainable mechanical flexibility for the sensor in wearable sensing systems.Many studies have been focused on developing efficient, flexible, and highly sensitive UV photodetectors from various nanostructured materials. As an emerging nanomaterial for effective flexible photodetectors, 2D nanomaterials have attracted considerable attention because of their unique properties, such as atomic-scale thickness, lightweight, and flexibility. [8,9] One representative 2D nanomaterial, layered double hydroxides (LDHs), has received considerable attention owing to their novel optical, electrical, structural, and electrochemical properties. [10][11][12][13][14] LDHs are functional clay composed of an interlayer anion and a host layer that is positively charged in a layer-by-layer structure. The general chemical composition of LDHs can be described in the formula [M 2+(1-α) N 3+ (OH) 2 ] α + [A n− ] α/n •mH 2 O, where M 2+ is the divalent cation (e.g.

Persistent Photoconductivity Control in Zn-Doped SnO2 Thin Films for the Performance Enhancement of Solar-Blind Ultraviolet Photodetectors

“…The photocurrent ( I ph ) increases continuously as the light intensity ( P ) increases, as shown in Figure c,d. The photocurrent depends on the light intensity by the power law, I ph ∝ P η . , The exponent (η) is the empirical coefficient implying the information on the charge traps of the photodetectors. The exponent value of η = 1 indicates the ideal trap-free condition.…”

“…As the internet of things technology developed rapidly, the ultraviolet (UV) photodetector has been a very significant functional component in many applications, such as secure wireless communication, wireless control system, environmental monitoring, biological/chemical analysis, and image sensors. − Especially solar-blind UV photodetectors have attracted tremendous attention in environmental, industrial, military, and biological applications. Representatively, in military applications, a UV photodetector can be used for early missile plume detection as a missile warning receiver to find the missile by detecting the UV light coming from the missile’s motor. − In general life, the UV photodetector has been used in the medical field, such as dental care and dermatology, to detect UV exposure during removing the organics in teeth or germs. , Although the sun is the primary source of UV light, no photons in the UVC spectral range (200–280 nm) exist within the Earth’s atmosphere because it is typically absorbed by the ozonosphere when it passes through the atmosphere.…”

Synergistic Coupling of Tribovoltaic and Moisture‐Enabled Electricity Generation in Layered‐Double Hydroxides

“…The ZnAl-LDHs were grown using hexamethylenetetramine (HMTA) and zinc nitrate solution at 90 °C for 1 h. In this study, among various LDHs, ZnAl-LDHs were selected because of their semiconducting properties and easy formation of scrolled sheet structures with very thin layered pores. [30,31] ZnAl-LDH can be formed through a reaction between Zn 2+ present in the solution and Al 3+ supplied from the Al seed layer deposited on the surface of the Si wafer. The thickness of ZnAl-LDHs was controlled by adjusting the thickness of the Al seed layer because the thickness influences the amount of water molecules absorbed and their concentration gradient, as shown in Figure S1b (Supporting Information).…”

“…Therefore, LDH would exhibit excellent self-hygroscopic characteristics, and the high-density scroll structure with fine pores can maximize this effect. [29][30][31] In particular, ZnAl-LDH is expected to exhibit high MEG characteristics because its constituting Zn and Al elements have high chemical reactivity with water molecules. [28,32,33] LDHs can also be a promising TVNG material because their semiconducting characteristics represent electron excitation through various energy sources based on tribovoltaic effects.…”

“…[28,32,33] LDHs can also be a promising TVNG material because their semiconducting characteristics represent electron excitation through various energy sources based on tribovoltaic effects. [28][29][30][31] Nevertheless, to the best of the authors' knowledge, there is no report on the tribovoltaic effect and ME in the LDH structures. Therefore, if the tribovoltaic and ME can be verified in the LDH structures, they can generate electric charges even under humid conditions.…”